Astr110 Photography Projects, Fall 2006

M77 Spiral Galaxy, Nate Vander Plas

This is a picture of the spiral galaxy Messier Number 77, originally discovered by Pierre Méchain on October 29, 1780. It was later seen by Charles Messier who mislabeled it a "cluster with nebulosity" on December 17 that same year. M77 turns out to be one of the first discovered spiral galaxies and one of the biggest galaxies in Messier's catalogue. It is approximately 60 million light years distant from Earth and is traveling away from us at a speed of 1100 km/sec.

M77 is a spiral galaxy just like our own galaxy the Milky Way. The center of M77 is a bright cluster of stars about 120,000 light years across and the spiral arms extend 170,000 light years. The inner region is populated by older, more yellow stars and the outer parts (the arms) are younger, slightly more blue stars. The approximate diameter of the visible part of my image is 3 arc minutes. By using this and the distance from Earth (60 million light years), I could use the small angle formula and calculate that the visible part of my image is about 52,360 light years across.

References:
Kronberg , Christine . "Messier 77." SEDS (Students for the Exploration and Development of Space). 20 Sep. 2005. SEDS. 16 Nov. 2006 <http://www.seds.org/MESSIER/m/m077.html>.